HTML Validator

The errors and warnings are generated by Tidy, originally developed by the W3C. Tidy tries to correct HTML errors by classifying them in 2 categories:

Critical HTML errors that Tidy cannot fix or understand.
Warning:
HTML errors that Tidy can fix automatically.
Good:
Or show the green icon, when there is no HTML errors.

If you have only warning warnings, press the Clean up button and Tidy will try to present a cleaned version of your page.

Other icons

Charset:
The document contains characters that do not exist to the specified charset. The document can not be checked.
No data:
The HTML cache is empty. The validation can not be done.
Disabled:
HTML Validator is deactivated.
Not in domain:
The URL is excluded by the Domain List defined in the options.

Extension homepage: http://users.skynet.be/mgueury/mozilla/